Bad direct injector?

[razorlab]

Is 5000 psi when cruising too high?

That is the HPFP pressure. LPFP side should be like 60-80psi

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[MOA90]

That is the HPFP pressure. LPFP side should be like 60-80psi

Ahh yeah I was mixing those up, but is it incorrect to assume that if my HPFP is in normal ranges that my LPFP is feeding it correctly? I can certainly check the LPFP psi as well.

 

[razorlab]

Ahh yeah I was mixing those up, but is it incorrect to assume that if my HPFP is in normal ranges that my LPFP is feeding it correctly? I can certainly check the LPFP psi as well.

Yes, if your logged HPFP angle is below 126* and the HPFP pressure is dropping out, it is most likely the LPFP having a hard time keep up.

Keep in mind, the HPFP is run off a PID system so having some smooth dips can be normal.

 

[MOA90]

Yes, if your logged HPFP angle is below 126* and the HPFP pressure is dropping out, it is most likely the LPFP having a hard time keep up.

Keep in mind, the HPFP is run off a PID system so having some smooth dips can be normal.

Ok, I'll check those out. Thanks! The thing that is strange but maybe I just don't understand is my fuel trims are very rich so that would indicate, in my opinion that the LPFP isn't having a hard time keeping up. Or am I wrong on that as well?

 

[razorlab]

Ok, I'll check those out. Thanks! The thing that is strange but maybe I just don't understand is my fuel trims are very rich so that would indicate, in my opinion that the LPFP isn't having a hard time keeping up. Or am I wrong on that as well?

LPFP and HPFP will have zero issues keeping up at non WOT if they are both healthy/installed correctly.

 

[MOA90]

LPFP and HPFP will have zero issues keeping up at non WOT if they are both healthy/installed correctly.

That makes sense but my issue is typically noticeable at idle and returning to idle. When cruising it sounds and drives pretty normal. I have only driven it very lightly since this issue has occurred to do tests so I haven't gone WOT.

 

[razorlab]

That makes sense but my issue is typically noticeable at idle and returning to idle. When cruising it sounds and drives pretty normal. I have only driven it very lightly since this issue has occurred to do tests so I haven't gone WOT.

I can't remember, are your trims positive or negative?

 

[MOA90]

I can't remember, are your trims positive or negative?

When I logged them last they were in the -20’s for LTFT and range from -5 to +20 for STFT.

 

[Thraxbert]

Have you ever smoke tested your intake side? That's another diagnostic that I don't recall in the thread's post history. Perhaps you have a significant leak somewhere, and the car is hunting, to the extent that it's tripping cylinder 1.

Grasping at straws some more:

• How are your MAP sensors? Are you 100% positive?
• Can you swap the low pressure fuel pump controller ("EKP") in the trunk with someone else's Supra for a few minutes?
• You are 100% positive that no PI injector is firing? You've unplugged them all?
• What is your engine coolant temp reading on OBD?
• Have you tested or replaced your O2 sensors in the downpipe? If you want to test them, please post voltage logs for these sensors over the course of a long drive.
• It would be a lot of work, but: have you swapped the injector to another cylinder? This needs special tools and a new injector o-ring.
• How's your catalytic converter honeycomb? Blocked cats can make rich trim.

 

[MOA90]

Have you ever smoke tested your intake side? That's another diagnostic that I don't recall in the thread's post history. Perhaps you have a significant leak somewhere, and the car is hunting, to the extent that it's tripping cylinder 1.

Grasping at straws some more:

• How are your MAP sensors? Are you 100% positive?
• Can you swap the low pressure fuel pump controller ("EKP") in the trunk with someone else's Supra for a few minutes?
• You are 100% positive that no PI injector is firing? You've unplugged them all?
• What is your engine coolant temp reading on OBD?
• Have you tested or replaced your O2 sensors in the downpipe? If you want to test them, please post voltage logs for these sensors over the course of a long drive.
• It would be a lot of work, but: have you swapped the injector to another cylinder? This needs special tools and a new injector o-ring.
• How's your catalytic converter honeycomb? Blocked cats can make rich trim.

First off I want to say thank you for all you suggestions, I really appreciate it! I have done a smoke leak test but not sure if the smoke was able to get into the intake manifold as most of the smoke was leaving through the air filter. I want to give this another go but not need to figure out a better place to introduce the smoke. Here are the answers to your other questions:

• How are your MAP sensors? Are you 100% positive? - I swapped this sensor in my intake pipe with a buddy and it didn't behave any different, I believe this is the MAP sensor.
• Can you swap the low pressure fuel pump controller ("EKP") in the trunk with someone else's Supra for a few minutes? - I would love to try this but didn't know about this until the other day, do you have any information on where this is exactly?
• You are 100% positive that no PI injector is firing? You've unplugged them all? - I have trusted that my tuner turned off my PI in a tune file he sent me while trying to troubleshoot this. I haven't unplugged them though.
• What is your engine coolant temp reading on OBD? - I haven't looked at my coolant temp through OBD but my stock gauges show normal coolant temps. I will add this to the list of things to look at as well though.
• Have you tested or replaced your O2 sensors in the downpipe? If you want to test them, please post voltage logs for these sensors over the course of a long drive. - I swapped a buddy's O2 sensors and it didn't change anything, unfortunately.
• It would be a lot of work, but: have you swapped the injector to another cylinder? This needs special tools and a new injector o-ring. - I haven't done this but did buy the injector puller tool in case I needed to swap out an injector. I did test my injector pressure after reaching operating temperature and shutting the car off. The pressure climbed instead of fall so I assumed my injectors aren't leaking.
• How's your catalytic converter honeycomb? Blocked cats can make rich trim. - I'm catless

 

[razorlab]

You would have to code the EKP to the car with something like Protool. I did that exact same thing last year at Grid Life with my EKP trying to diagnose a fueling issue on another Supra.

 

[Thraxbert]

The EKP is in the trunk under the deck lid. It looks like this. One plug and two 10mm nuts to swap it.

For the smoke test, you need a smoke test adapter with an inflatable balloon. Start the test from the air filter inlet pipe, and the inflatable balloon blocks it off + introduces smoke into the system.

//edit: there's also the MAP sensor in the manifold. Did you try swapping this one also?

 

[MOA90]

You would have to code the EKP to the car with something like Protool. I did that exact same thing last year at Grid Life with my EKP trying to diagnose a fueling issue on another Supra.

I don't have Protool but I do have BimmerLink, not sure if I would be able to use that for programming the EKP.

 

[MOA90]

The EKP is in the trunk under the deck lid. It looks like this. One plug and two 10mm nuts to swap it.

For the smoke test, you need a smoke test adapter with an inflatable balloon. Start the test from the air filter inlet pipe, and the inflatable balloon blocks it off + introduces smoke into the system.

//edit: there's also the MAP sensor in the manifold. Did you try swapping this one also?

Ok, I'll do that with the smoke leak test and block off the intake. Thanks!! Also, I haven't swapped any sensors on the intake manifold. I can look that up on where that's at unless you have a pic handy.

 

[MOA90]

I was able to test compression on cylinder 1 and it was good, around 220psi. I also did the smoke leak test again but sealed off my intake this time and had no leaks.

I wasn't able to try and swap my MAP sensor or EKP module with my buddy. Still unsure if it requires programming.

I also want to confirm that my engine coolant temp sensor is reading correctly. If none of those are the issue I’m genuinely out of ideas and might need shop recommendations.

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